1. Field of the Invention
The present invention relates to a disc case capable of accommodating a disc-shaped signal recording medium, such as a magnetic disc or an optical disc.
2. Related Art of the Invention
A conventional disc case disclosed in Japanese Utility Model No. Hei 6-2132 is described below referring to FIG. 31, a perspective view showing the conventional disc. The main unit of a disc case 80 comprises an upper half 81 and a lower half 82 so as to form a disc accommodation chamber 87. The upper half 81 and the lower half 82 of the main unit of the disc case 80 are each provided with an opening 85 (see FIG. 32). In addition, the main unit of the disc case 80 is provided with a shutter 83 being slidable in the direction indicated by arrow F or G. The shutter 83 covers the openings 85 formed in the disc case 80. The openings 85 are formed (1) so that a chucking member (including a disc table) can externally pressure-contact a disc 86 accommodated inside and (2) so that an optical head can gain access to the signal recording surface of the disc 86. The openings 85 communicate with the accommodation chamber 87 accommodating the disc 86.
In case the shutter 83 covers the openings 85 as shown in FIG. 31, a pair of engagement holes 84 provided in the shutter 83 engage a pair of elastic pawls 88 (see FIG. 32) provided on the main unit 80 so as to prevent the shutter 83 from sliding in direction F or G.
The shutter 83 is opened to expose the opening 85 as described below. In order to release the elastic pawl 88 engaging one of the engagement holes 84, an engagement release member (release pin) (not shown) is inserted into the engagement hole 84. While being kept inserted in the engagement hole 84, the engagement release member is slid toward the other engagement hole 84, thereby opening the shutter 83.
The shutter 83 now being opened is closed as described below. The engagement release member remains inserted in the above-mentioned engagement hole 84. When the engagement release member is moved to its original position, the shutter 83 covers the exposed openings 85. After the shutter 83 covers the openings 85, the engagement release member is extracted from the engagement hole 84. Instead of the engagement release member, the elastic pawl 88 engages the engagement hole 84 so as to restore the lock condition.
The above-mentioned opening/closing operation of the shutter 83 is performed when the disc case 80 is inserted into or taken out of a signal recording and/or reproducing apparatus (player).
Consequently, the shutter can be opened and closed positively.
However, since the above-mentioned conventional disc case is not dustproof sufficiently, there is the danger of entry of dust into the accommodation chamber. More specifically, a concave portion 89 is formed in the range from the opening 85 to the front fringe portion of the case so as to decrease the amount of movement when the disc is dropped onto a disc table. Therefore, dust entered from the engagement holes 84 formed in the shutter 83 to the interior of the disc case 80 can further enter the accommodation chamber 87 via the concave portion 89.